In 1817, Desmarest erected Eryon cuvieri, a new crustacean from the Late Jurassic of Bavaria (southern Germany). Later, the same taxon was described as Macrourites arctiformis by von Schlotheim (1820). Subsequently, numerous authors, probably unaware of Desmarest's first paper, referred to this taxon as Eryon arctiformis (von Schlotheim, 1820). Following the Principle of Priority, the original name must be used and Macrourites arctiformis von Schlotheim, 1820 is here considered to be a more recent, subjective synonym. Moreover, two specimens of the type series of Eryon cuvieri Desmarest, 1817, from Faujas de Saint-Fond's Cabinet of Natural History, have recently been traced in the Collection de Géologie of the Muséum national d'Histoire naturelle, Paris. A lectotype is herein designated.